[Python-Dev] Adding a conditional expression in Py3.0

[Michael Urman]

On 9/23/05, Nick Coghlan <ncoghlan at gmail.com> wrote:
> But I think there's a difference in kind here - to *fix* Raymond's example
> required a fundamental change to the structure of the line, none of which
> looked as clean as the original. There is no way to get the and/or construct
> to gracefully handle the case where the desired result in the 'true' case
> might itself be false: either you change to using an if statement, or you use
> a workaround like the ugly singleton-list approach.
>
> That is, the following is fundamentally broken for pure imaginary numbers:
>    return isinstance(z, ComplexType) and z.real or z

It's hard to say whether this fixes Raymond's example when the goal
wasn't clearly stated, but I find a non ternary option

    lambda z: complex(z).real

more readable than any of the variants proposed so far. The obvious
downsides are that it can raise a ValueError, and turns integers into
floats. But if the input list is all numeric, it has clean results.

--
Michael Urman